The present invention relates to glazing systems such as storefronts, curtainwalls, etc. and in particular to such walls which include horizontal and vertical frames supporting large panels of rigid material.
Usually such walls are glazed and include mullions and base plates which receive and support glass panels with suitable flexible gaskets surrounding the glass panels to make a water tight seal between the supporting frames and the glass panels.
Invariably these curtain walls are designed for a particular glazing assembly or glazing package having fixed dimensions for a relatively permanent installation.
In addition, these glazing installations are designed usually to support loads generated by ordinary storefront plate glass and do not include adequate structure to support much heavier loads such as are generated by bullet resistant glazing assemblies.
That is, no change in the design or configuration of the curtain wall structure is contemplated other than the replacement of defective gaskets and broken glass panels, as the case may be.
Prior art patents pertinent to the disclosure over which the present invention is an improvement are U.S. Pat. Nos. 3,380,210, 3,638,385 and 4,625,659.
While the '210 reference discloses a filler piece 72the frame structure is not of sufficient strength to support bullet resistant glazing assemblies and the frame, in general, is not secure from ballastic projectiles.
While the '659 reference discloses a security window or door structure, there is a substantial opening about the periphery of the channel frame which provides access for deflected projectiles entering through the ventilation gap 12. The '659 concept incorporates a pressure equalization chamber for absorbing explosive energy. The system is designed for a single original installation with no provision for modification or retrofilting.